Back rest for bathtub



FIG. 1 is a perspective view of my back rest for bathtub shown in placefor use in a bathtub, the broken lines partially showing the bathtubbeing for illustrative purposes only and forming no part of the design;

FIG. 2 is a front view of my back rest;

FIG. 3 is a back view of FIG. 3;

FIG. 4 is a left side view of FIG. 3;

FIG. 5 is a right side view of FIG. 3;

FIG. 6 is a top view of FIG. 3; and,

FIG. 7 is a bottom view of FIG. 3.

The ornamental design for back rest for bathtub, as shown and described.